"There is an awe" being in the same room with a massive animal, said Winter, who performed dental exams. He found a fractured tooth causing some pain in Jabir's upper lip, but everything else looked good.

Sandy Wilson, an associate veterinarian, said the zoo plans to examine all eight of its gorillas.

The same exam was performed on the zoo's youngest gorilla, Virgil, several months ago and he had a perfectly normal heart, Wilson said.

Danielle Decker, a senior zookeeper with the Downing Gorilla Forest, said staff trained for the exams for three to six months. They taught the gorillas to hold their arms out for an injection, moved them to different rooms and practiced giving injections with different widths of needles.

"Training helps us do preventative care," Decker said. As an example, she said, the gorillas open their mouths to let staff brush their teeth.

Doctors plan to perform similar exams on the zoo's older silverback gorillas, which can weigh as much as 500 pounds.